Persons having little or no muscular control of the legs usually have to work and operate from a seated position.
Standing up and working while standing up greatly increases mobility of a person and produces physiological benefits, relieves pain, boosts morale and makes a person more independent.
The benefits of standing are best realized when a person can quickly convert a highly mobile wheelchair to a standing aid.
It is highly desirable to construct a standing aid so that it does not reduce the mobility of the wheelchair.
Stability is an absolute requirement of a standing aid. It is highly desirable to have as broad a base as possible and to have as low a center of gravity as possible, both when the device is used as a standing aid and when the device is in its stored position.
In the use of wheelchairs, it is important to reduce weight of the chair to minimize energy required for operating the chair. Effort required for chair operation is directly related to the weight of the chair. Starting, accelerating, slowing, turning, stopping and backing all require effort which is directly related to the weight of the chair. It is highly desirable to make any attachment as lightweight as possible.
It is extremely important that a standing attachment be quickly movable into a standing position and into a stored position with as little effort as possible. It is highly desirable that the device be capable of being assembled and stored with minimal movements of the user.
Wheelchairs are designed with elements of high functionality. One example is the footrest on wheelchairs. To operate wheelchairs in confined spaces and small turning areas it is important that footrests be movable and removable, for example. It is highly desirable that an attachment for wheelchairs be made so that it does not reduce or make more difficult the functioning of existing chair elements.
For those who live and work in wheelchairs, there are some overriding considerations for any assistance device which is to be attached to the wheelchairs. They are weight, bulk, convenience and safety.
Each additional pound added to a wheelchair increases the workload of propelling it. That it is especially significant to the user who is active and uses a wheelchair to travel considerable distances. It is important to use the minimum amount of material and weight in the assistance attachment which is necessary to accomplish the desired function.
A standing attachment must stand rigidly by itself and withstand horizontal forces exerted by the user while pulling into the standing position and while standing and working.
It is highly desirable in any attachment device that the attachment pieces be limited and that, where possible, the pieces be multifunctional, that is, functioning in the stored position as well as in the standing position. That is important for two reasons, the reduction of weight and the convenience of using the device and moving the device between standing and seated positions and disassembling the device. It is important that the elements of the device be firmly locked in place without danger of failure.
If wheelchair attachments extend in any direction past the normal dimensions of wheelchairs when in the stored or seated positions, additional problems are created for users of the wheelchairs. Active wheelchair users must be able to maneuver in small spaces such as those found in the workplace or while travelling, especially in motel or hotel bathrooms. Any increase in the functional dimensions of a wheelchair is undesirable since it decreases maneuverability in confined spaces. In addition, any extension to a rear of a wheelchair can increase difficulty of an assistant who may push a wheelchair.
It is extremely important that all parts of a device not encumber the travel of the wheelchair. If any part of a device in a stored position would hang near a floor, for example, that could cause problems when traversing on even terrain or moving over curbs or pulling a folded chair into a car, for example, because a hanging member could hit a protruding surface and damage the device or stop the progress of a wheelchair.
Low center of gravity is important, and it is extremely important that both the user as well as the wheelchair have low centers of gravity. It is important when using a standing device that the user be in the lowest possible position, with feet resting on the ground. It is also important that the ground contacting outline of the device be well outside of the user's position. When standing in a device where a user's center of gravity is very close to alignment with a point of contact on the floor, an even slight forward lean could create a distinct possibility of toppling forward, for example. That is especially true for tall or heavy individuals, since the only thing to prevent tipping would be the weight of a wheelchair, which is intentionally constructed as lightweight as possible.
One of the most significant advances in wheelchair technology was the development of footrests which unlock and swing out to a lateral position from which they can be dismounted from the wheelchair easily. It is important not to interfere with that function, since it is often necessary to temporarily remove footrests to approach closer to various objects to more safely transfer to things such as, for example, bathtubs and seats in automobiles. It is often necessary to remove footrests or swing them out laterally because a wheelchair user's feet may extend too far forward to fit under some desks or tables, or because there is insufficient room to maneuver in small rooms such as restrooms, which are not wheelchair accessible, but must be used nevertheless.
Wheelchair brakes work well when a user is seated in a wheelchair. Although provisions have been made to securely lock wheels of a wheelchair, when the user is standing there is little weight on the wheelchair wheels, and their ability to prevent movement is limited. It is important that a standing device provide means to prevent movement during use.
Many persons with paralyzed legs have a lack of lateral stability in knee and ankle joints. That can result in the outward bowing of legs while standing. It is extremely important to provide a solution to that problem.
Most wheelchair manufacturers will not honor warranties for frame breakage or malfunction if a frame of a wheelchair has been altered, and especially if anything has been welded to it. It is important that any device attached to a wheelchair not alter the manufacturer's frame and not weld materials to the manufacturer's frame. Besides voiding warranties, altered frames and welded attachments increase the complexity of installation and prevent disassembly of a chair and its attachment for travelling.
When travelling, it is extremely important to be able to pack and ship attachments. Attachments which are large or which are permanently attached to chair frame members are difficult to ship or require special containers or considerations.
Many problems remain in the attachment of devices to wheelchairs to facilitate increased and varied use of the wheelchair. The problems are especially notable when providing standing attachments for wheelchairs.